


Life Finds a Way

by sheron



Category: Supernatural
Genre: Action/Adventure, Canon Compliant, Castiel & Dean Winchester Friendship, Castiel & Sam Winchester Friendship, Dean Winchester & Sam Winchester Are Brothers, Dinosaurs, Friendship, Gen, Jurrasic Period, K-Pg extinction event, K-T extinction event, Mythology - Freeform, POV Dean Winchester, POV Sam Winchester, Season/Series 10, Survival, Team Free Will, Teamwork, Tyrannosaurus rex - Freeform, Wilderness
Language: English
Status: Completed
Published: 2016-02-01
Updated: 2016-02-01
Packaged: 2018-05-17 17:32:38
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,334
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5879617
Author URL: https://archiveofourown.org/users/sheron/pseuds/sheron
Summary: <blockquote class="userstuff">
              <p>As Legacies, they had a responsibility to diffuse any cursed objects Magnus had left behind; they should have expected it to be a death trap. But nobody expects to be sent to face one of the most terrifying monsters the Earth has ever seen. Life...uh...finds a way, a.k.a. Winchesters vs. T-Rex!</p>
            </blockquote>





	Life Finds a Way

**Author's Note:**

  * For [kuwlshadow](https://archiveofourown.org/users/kuwlshadow/gifts).



> This was written for a prompt in the 2015 SPN Reverse Bang challenge by [kuwlshadow](http://kuwlshadow.livejournal.com/16442.html), who also made the gorgeous banner for this story. I'm grateful to her for the idea and to the moderators for running the challenge.
> 
> I'd like to thank wonderful [NyteKit](http://archiveofourown.org/users/NyteKit) who betaed this in the blizzard, up-hill both ways. I'm lucky to have her help!
> 
> The story is set after 10x19 - The Werther Project, so possible spoilers up through that episode.

  


  


 

* * *

 

"This is darkest sorcery," Cas had said. "Be on your guard."

"Hey, Dean, that's a really creepy-- wait--No! Don't touch that!" Sam had said.

There was a brilliant flash of light.

 

* * *

 

Only twenty-four hours prior, Sam had been the one convincing Dean that they had a responsibility to diffuse whatever other cursed objects Magnus had left behind. Men of Letters, blah, blah, blah, Legacies, blah, blah, blah. This time around it had seemed prudent to get the re-powered angel involved just in case they got trapped again; and although Castiel couldn't teleport to their exact location anymore, the speed with which he had made it to the latest safe-house Sam had found in Montana was remarkable. Dean hadn't remarked on it, but instead busied himself with examining a strange little black statuette in one of the boxes that seemed to absorb all the light that touched it. It had been a curious thing, reminiscent of a nesting bird or a shrub. The Mark on his arm had been buzzing as though it sensed power all around them. Magnus had been a douchebag ( _\--a dead douchebag, whispered the Mark, pulling up the memory of slicing through his neck like butter--_ ) but he had been one of the most powerful wielders of magic they had ever encountered. Nearby, Sam had been leafing through one of the dusty books with a frown of concentration until at the last moment he had looked up, his expression changing to concern.

All of this flashed through Dean's mind spelling trouble even as he spit out the ash that had ended up in his mouth after the ungainly collapse into-- what felt like a burned down forest. The air smelled strongly of rotten eggs and burning wood, as if he needed any more adrenaline coursing through him.

"Sam?" He looked up, twisting to look around him. 

He heard a groan from his left, as familiar as the back of his own hand, as Sam slowly sat up near him, wincing. Dean could barely see in the darkness, but he looked to be in one piece.

"Cas?" Dean shakily got to his feet. They were in the middle of a gigantic field that had burned down to cinder long enough ago to have the remaining coals completely extinguished. A cold wind blew through the open stretch of the land. It had been fall in Montana, but this was colder still. "Cas!" He called, feeling a certain amount of trepidation now. He'd touched the figurine; now this. Dean had a feeling he would be hearing from Sam shortly on that subject and wanted to postpone that conversation.

"You alright?" He asked in the meanwhile, without looking towards Sam, still scanning the horizon for any sign of Castiel.

"Where do you think we are?" Sam was wincing and clutching his wrist. Dean gave him another once over and Sam admitted, "Sprained, I think." Sam tried to smooth out any pain in his expression. "I don't see Cas."

"He must be around here somewhere. You were both right next to--" he saw the other man lying against one of the burned down tree trunks. "Cas!"

"I can't see any stars," Sam said, glancing up as they stumbled towards Cas. "Did you just wake up? How much time did we lose?" It was difficult to say. The clouds must have been blocking visibility because the sky was dark but it didn't feel like night. Some stray sunlight was filtering through the atmospheric layer above to reach them making it feel like twilight right before dawn. Their eyes slowly adjusted to the low light so Dean was finally able to spot Castiel. They reached him simultaneously and crouched on each side of him. Dean pulled out a small flashlight from his back pocket and shone its blue beam onto Castiel's face. 

Cas startled at the light and groaned softly making Dean turn it off. "Hey, man..." Sam tapped Castiel's cheek and said to Dean, "He seems to have landed badly." That was an understatement. Even if the blood that was trickling from Castiel's nose and ears was invisible without the flashlight, Dean could still smell it now that they were close. It mixed with the smell of sulfur making him dizzy.

Slowly, Cas opened his eyes and they waited for them to focus. "You're alright," his voice was gravel and he coughed. The words triggered a memory in Dean of another time and place when Castiel had been lying in a similar position, bleeding against an old car because he'd taken himself to the limit. The bad feeling he was having intensified, and with it rose the singing of his blood, like a war drum. 

"Cas, do you know where we are?"

"When," Cas croaked.

They paused. Dean swallowed. 

"Dammit, Dean," Sam said with a tone of heavy disillusionment.

Dean barreled on. "You mean we traveled in time? Is this the Apocalypse we're looking at?" Last time he had at least been in a populated area. This looked like the middle of nowhere, a dead forest, and not a sign of life or civilization besides them. He slapped his coat's pocket for his cell-phone, intending to check the signal at first opportunity. It was difficult to speak with all the ash in the air and he had to swallow against his parched throat.

"We were sent to the past." Castiel licked the blood of his lips and shifted so he could tilt his head up and look into the sky. "Far into the past." 

Dean's eyebrows lifted involuntarily. Not the Apocalypse then. Something inside his chest eased. From the moment he'd woken up a large part of him believed he'd caused this devastation somehow. 

Sam craned his neck to look up as Castiel was doing, but his eyesight wasn't any better than Dean's, he could see nothing above them. It was as though they were under an artificial ceiling instead of the sky. "How far? Where are we Cas?"

"I believe in your time this area will become known as the Hell Creek Park." Castiel sighed and ceased his observation of the sky. His shoulders slumped. "We are roughly sixty five million years into your planet's past."

 

* * *

 

After those little words, things started moving very fast. Sam had drawn in a breath with too much ash in it and started coughing explosively. Beside him, Castiel groaned and tried to rise even as Dean rushed to assist him with a hand under the elbow. Then, there was a heavy sound of an impact against the ground, the reverberations echoing through their bodies. They stilled. It was the first time Sam had noticed the complete lack of sounds of birds. Everything was starting to make sense to Sam, even the sunlight blocked almost completely by the cloud of debris. They were in the middle of the impact winter. The Chicxulub asteroid was the cause of the blocked sun, leading to the cold that was chilling them to their bones and was likely also what had altered the environment enough to cause the firestorms that had ravaged this place. 

Another dull thud that went right into their bones. In the near complete darkness, Sam strained his eyes to see around them. Dean more or less yanked Castiel to his feet; he was already looking for cover in case they had to get mobile soon. Sam joined them standing, and tried to choke off his coughs as they listened.

"What is...?" Dean had trailed off. He was staring into the dark ahead, his expression puzzled.

"Sixty five million years!" Sam hissed at Dean. He couldn't believe his brother still hadn't put it together. Seconds had passed since the first sound of the impact and still he felt like they were idling. "You were right the first time. It is the Apocalypse, just not for humanity. It's the end of another world."

"I don't think all of them went extinct," Castiel answered Sam's guess as he too turned towards the sound of the impact of heavy footsteps on the ground. The two of them were on the same page, at least.

"Wait..." Dean's voice rose incredulously. He didn't finish and pulled out the flashlight and shone it into the dark ahead. There was a screeching sound, almost like a roar but one that had come out of bird's throat.

"We need to get out of here!" Cas said, urgency clear in his voice. He grabbed at Sam's elbow, whether to urge him on or just to steady himself Sam wasn't sure. "I cannot fly. I can't take you home. When we were sent here, we were meant to be present for the asteroid impact. I tried to change our trajectory mid-flight and bought us some time, but we need to hurry."

"I'd love to get out of here!" Sam said. "What do we do?"

" _Run._ "

They ran. Or rather, Sam and Dean did most of the running, with Castiel more or less dragged between them, his right arm thrown across Dean's shoulders. Sam supported him with the arm that wasn't sprained. He wished he had his shotgun. 

"Which way?" Dean cried out as they dashed in a seemingly pointlessly random direction, simply opposite from the sound of heavy footsteps. The dull impacts against the earth were getting closer. Whatever made them had to be humongous and Sam had no desire to find out if his best guess was correct. Later, when they were safe (or as safe as their lives ever got) he would grill Castiel about everything to do with this place. Right now, he wanted to survive. They needed to find cover, or possibly water if it was tracking them by scent. He couldn't remember if they hunted in packs. Or was that the other guys, the Velociraptors?

"Which way?" Dean shouted again. "We can't keep going in a straight line."

"There might be...water that way." Castiel indicated with his head.

"How do you know?" Dean panted as they stumbled around a collapsed trunk of a burned tree, footsteps lifting clouds of ash into the air.

"I can hear the waterfall," Sam said.

"Alright. We'll lose him there."

"It's a she." Castiel murmured, but they were too busy dragging him along toward the edge of the cliff to pay his words any mind. The sound of falling water was indeed getting closer and with it the intense smell of acid and rot. Sam was dizzy with it. The air clung to his tongue, burned his throat and nostrils, and his eyes itched. Dean was starting to cough as well, the closer they got to the water-source.

"That smells like...hell." Sam said when they finally the cleared the last line of burned down trees, stumbling towards the edge of a steep downward slope. It was barely climbable, and certainly not in a hurry. The river ran down the edge into the ravine below. The water rushed in a powerful current, foaming where it hit the jagged edges of rocks. They couldn't see to the bottom of the ravine even with a flashlight's beam shining down against the yellow-tinted water. Jumping in feet first was out of the question if they didn't want to hit the sharp rocks likely to be at the bottom.

Leaving Dean supporting Cas, Sam silently crouched down and tried to feel the side of the cliff to see if they could climb it. The rock felt jagged even underneath the black dirt that instantly clouded up under his quick examination and settled all over his hands and face. Sam had a strong urge to throw up but he had practice dealing with that. He pulled his cotton shirt up to cover his nose, trying to breathe that way, still choking over the thick, clogging smell. 

Dean shone their only flashlight into the path behind them. Normally Sam would have railed against that, but the creature that was following them was already aware of their location, and if the sounds of its footsteps were anything to go by it was picking up speed. They were running out of time. Sam realized that they would have to jump.

"If we get a running start," he theorized, trying to figure out how they would deal with the possibility of being separated in the water, and how they could make sure Cas didn't sink like a stone (it wouldn't kill him, but...). He glanced behind them, seeing the shape of the beast chasing them come into view from behind the burnt down husks of trees. For a long moment he couldn't tear his eyes away.

Dean turned to Sam, and his face had a mix of wonder and disbelief.

"Dude," he said, flatly. "That's a friggin' T-Rex!"

"Yes," Sam said and then he couldn't help smiling a little as their eyes met. 

Their lives were weird.

"The predator currently pursuing us is extremely hungry." Castiel put in, helpful like that. "I am not sure even the significant amount of sulfuric acid in the water will deter it from a source of food."

"Wait-- Acid?" Dean craned his neck over the cliff and shone his flashlight down to the yellow water. "Why didn't you say so?"

"I assumed you could smell it." Castiel replied. They had, until the smell became so overwhelming it wasn't possible to even distinguish the individual chemicals anymore. Sam no longer wondered why he felt like throwing up. That stuff was toxic. "We need another plan."

"Yeah, because watching skin melt off my bones is one step down from death by dinosaur."

"I would be able to heal you, once I get my strength back." Cas assured them. "If we survive." That was actually good to know. Sam examined the drop ahead of them once more, wondering which was truly worse.

"Let's work on that 'if'." Dean said. He pushed Cas towards Sam, turned the flashlight on again, and ran sideways along the outcrop, drawing the beast away from them.

  


 

* * *

 

There were a few moments in Sam's life that his heart felt like it stopped for a moment before resuming it's beat. Almost all of them were in some shape connected with Dean. You'd think, the thought blazed peevishly through his head, that after thirty years he'd be used to this but no. Somehow, Dean found new and surprising ways to nearly give him a heart attack. Seeing his brother run away from him to distract a Tyrannosaurus Rex wasn't something you could prepare yourself for.

"Dean!" Sam shouted on instinct. He spared a distracted thought to Cas, who finally seemed to be taking most of his own weight. Maybe it was adrenaline, if angels could feel that.

"Go, Sam!" Dean shouted without looking back, all of his attention occupied by the monster that was now visible in the shadows. It was bright enough that they could see her dark form glitter slightly in the infinitesimal amount of light that came through the atmosphere. 

"Cas, start climbing down!" Sam ordered and raced after his brother. He didn't know how he would help, but he couldn't let Dean face this monster alone. If Castiel responded, Sam didn't hear it.

Running after his brother, Sam's mind raced for a solution, eyes tracking every object on the ground to see if it would help them in their fight. He only had his knife on him, and even Dean's gun might not make a difference. They didn't know how thick the monster's skin was. They didn't know where her vital organs were located. Ahead of him, Dean picked up speed and used the beam of the flashlight to draw attention to himself again. Sam felt as though the ground trembled with the answering roar. Then, terrifyingly, a different, higher pitched sound joined in from another angle. Sam realized they might be attracting attention of other predators in the vicinity. Anyone who lived in this hell of a burnt down forest had to be hungry. And right now, the other predators were invisible.

Farther away, Dean turned, his back against a burnt down tree and hiding him from the monster's line of sight. "You were supposed to climb down with Cas!"

"If you think I'm leaving you here, you're out of your mind." Sam shouted. The old tired resentment at the suggestion rose inside. The familiarity of the emotion cleared his head, made it easier to think.

"An actual T-Rex!" Dean said, paused breathlessly to look at the monster only some thousand feet away. 

Sam wished the high notes in his voice were fear and not excitement. The way the beast was moving, she was probably clocking at minimum of 15 mph, but her gate was uneven. The T-Rex favoured one hind leg over the other and Sam realized she was injured. Sam looked at the ash on the ground. If they rolled in it, combined with the smell of sulfur, it might mask their scents enough. Then the problem would be finding some cover bigger than a tree stump. Even so, it didn't look like there were many alternative food sources around. The beast wouldn't leave until it tracked them down.

Sam ran towards the edge, searching desperately with his eyes in the murky twilight. When he found what he was looking for, he turned to Dean with renewed hope. "There's a platform down there. We can climb down. It won't reach us!"

"Grab Cas and go!" Dean shouted back. They both looked back to see if Cas was where they left him, but he wasn't in sight. Sam met Dean's eyes in mute dismay and saw the split second of indecision before his brother's face hardened. "Go Sam! Start climbing down and I'm right behind you."

Sam knew this wasn't time to argue. They had minutes, if that. Glancing around for supports and finding them, he took a quick breath of air and crouched down, spreading himself against the ground. He tried not to breathe in the toxic dust that rose in the air with his movements, stretching his body down until one foot met the jagged edge of a stone. He lowered himself, moving too fast for the dangerous conditions, but knowing that he couldn't take more then a second to make sure of his footing. Ignoring the pain in his wrist, he moved as swiftly along the near vertical surface as he dared.

Closer now, the scaly, leathery thirty-feet monster out of nightmare was looking around. Her head turned towards Sam and Dean turned the flashlight on again, making the T-Rex's head snap back to him. The beam of bright light hit its eye, making it roar, and they saw for a moment a large golden iris of the apex predator.

" _Move_ , Dean!" He screamed, before lowering himself below the outcrop, and out of sight. 

"Their vision is based on movement!" Dean shouted back, in a strong, clear voice. Unafraid. "Haven't you seen the movies?!"

Lifting his head above the precipice one last time, Sam looked around for Castiel but the angel was nowhere in sight. They had to depend on him knowing how to survive on his own. Sam climbed further down, trying not to think about the height, focusing only on reaching the small platform about ten feet below the cliff's edge.

Just as his feet touched the rocky edge, he felt small rocks rain against the top of his head and looked up, shielding his eyes with a hand. Dean's back was just visible above the cliff, smaller rocks flying down from his feet. The sound of thudding footsteps seemed unbearably close.

"Dean!" it tore out of him. He couldn't see how close the monster had gotten. Sam almost started climbing back up.

Dean must have thrown the flashlight away from him, because his hands were empty as he too, lowered himself to the ground, and scrambled for purchase with his feet. Sam shouted directions as Dean rushed to make the dangerous way down in half the time Sam had had. 

There was a roar that Sam could swear ruffled the top of his head.

Dean jumped the remaining four feet or so, and Sam just managed to grab at his leather jacket, yanking him towards the side of the cliff as larger rocks flew over the edge and rained down on them. The jaws of the T-Rex snapped the air a few feet above Sam's head.

They both crouched down, making themselves as small of a target as possible. Sam's hands were frozen in Dean's brown jacket as they both stared above. The monster tried again. She was edging up to the very boundary that currently contained her, sending heavier and larger boulders their way. They ducked as well as they could, plastering themselves against the side of the cliff.

Again she tried to reach them with her jaws alone, her long scaly neck stretched to the limit. Again, fangs the size of his arm snapped just overhead, empty of their prey. On the side of her head, Sam had glimpsed signs of barely healed claw marks. With a strange pang Sam realized she might be just as hunted as they were by predators willing to take a risk with a larger beast rather than go hungry. There were a few seconds of respite, and then again, she strained for them.

"We can't stay here," Dean said. 

"I know. Eventually she'll figure out a way to her meal ticket."

"Cas!" Dean shouted loud enough to be heard at a distance.

Sam stared, wondering what Dean expected. Whatever it was, the monster at the top was getting smarter about the strategy of getting to them, crouching low on her short front arms. Her head was angled to the side so she could track their every move through the large amber eye. Sam felt like she was thinking as she watched them, the slit of her iris seemed to narrow.

With a quick, assured move, Dean lined up his gun and shot her right in the eye. This close, the impact tore apart the eye-socket, splattering the thick goop that had been the lizard's eye-ball fluid all over Dean. Some of it landed on Sam, making him recoil. The monster roared in pain, even as Dean dove back towards the face of the cliff away from the rocks that rained down at them as her trashing head reared up in agony. 

It worked long enough to distract the monster. What looked like a flash of white lightning shone nearby, and then the monster was roaring again. Then it was falling over the cliff's edge.

Sam and Dean barely had a split second to plaster themselves against the cliff as the full body of the monster fell past them. The silver angel blade could still be seen in its hind leg, piercing it through to the hilt. The beast screeched in pain and terror as she hurtled down the ravine among the rocks dislodged by her fall, the lizard's tail striking the edge of the outcrop on which they huddled, shielding their heads. She disappeared into the darkness below.

One of the larger boulders struck Sam as it fell, making him yelp a little, but after another moment, everything was quiet. He looked up at his brother. They were face to face, and Sam's hand was still holding on to the edge of Dean's dirty jacket. He felt about five years old.

"Didja see that?" Dean was grinning at Sam, a flash of teeth. The creepy little grin sent shivers up Sam's spine. Dean's hair was still dripping the goop of the dinosaur's eye fluid, and his face was dirty with soot and some blood. Sam didn't know if it was a boyish enjoyment of his brother on one of his crazier antics, or if it was the bloodthirstiness of the Mark that had Dean pumped about what he had done. 

Sam didn't have time to dwell on it. Castiel made his way to them, crouching over the cliff, his worried eyes running over their shapes to make sure they weren't injured. He looked winded and he had dust in his hair and all over his face. His black hair was plastered against his forehead with sweat. Sam didn't think he looked much better himself, if Dean's deranged appearance was any indication. His brother's leather jacket looked gray under the layer of dust.

"That should slow her down," Castiel said simply. "We'd best make haste."

"Let's get gone before we find out what else lives here."

 

* * *

 

"Explain to me again how we're sixty five million years in the past?" Dean said crankily after they'd been hiking at a semi brisk pace for about a half hour and had to stop, the two humans wheezing for air. Under normal circumstances a hike like that wouldn't have bothered Sam, but now he felt like his lungs were on fire. The chemicals in the air probably had something to do with it. Sam didn't know if he ought to be grateful that he had lost most of his sense of smell by now or if it indicated a bigger problem. He hoped Cas would be able to fix them later -- if there was a later. His head hurt from where the rock had struck him, but between all the aches and pains in his body it was hard to say what bothered him more. After climbing up-top, Dean had picked up the flashlight that he'd thrown away, and was now occasionally turning it on when the way became too hard to pick out in the semi-darkness. So far nothing else attacked them. Perhaps whatever else lived here was feasting on the body of the dinosaur that had fallen down the ravine.

Castiel trudged along, keeping his head down and keeping up with them. Dean said a few words about the lack of Impala to take them wherever they wanted to go, but even he probably realized they wouldn't have been able to drive in this landscape. It was too treacherous. Numerous times they'd had to go around large white bones lying on the ground, remains of some earlier monster picked completely clean. There was no plant-life. The only creatures alive were likely scavengers, like the T-Rex. 

"The object you touched had intended to send us back into the time of the asteroid impact," Castiel said lowly, clearing his own throat from the dust that seemed to be perpetually settling there. "I tried to alter our trajectory, but without my wings it was difficult. I brought us several years in the future from the moment of impact."

"Thanks, Cas," Sam said, trying not to think of how much damage the angel might have done to himself trying to fly on broken wings to avoid this catastrophe, "I guess if we'd been around for that we would have been toast?" 

"I am unsure if the infrared radiation would have killed you this far away. It would have been highly unpleasant."

"As opposed to this walk in the park," Dean muttered.

"So this is the impact winter?" Sam asked, getting the nod from the angel.

"Much of the dust and aerosols have settled by now, which is why we can breathe at all." 

Sam, wheezing nearby, wanted to argue that this could be called breathing. It had started to drizzle, only just enough to be annoying, but the wind was picking up and carrying the swirling dust and ash up into their faces. He spat out the sand that made his way into his mouth, it tasted like clay.

"The existence of aerosols in the stratosphere still blocks most of the solar radiation and prevents photosynthesis. There are almost no live plants left in this part of the world. The animal population on land is slowly starving to death. The acid that rained down from the air and ended up in the rivers and oceans changed the acidity of the water and caused the extinction of a great number of marine species."

"And where were your buddies during all this?" Dean said. "Where were the other angels?" They'd stopped, both to look around and to catch their breath. Everything they'd come across so far spoke of a level of devastation that Sam hadn't been able to even imagine until now. The closest comparison he could draw on was to pictures of the area of a nuclear bomb impact ... or Hell.

Castiel tilted his head to the Heavens. If he felt sad at the reminder of his family, he hid it well.

"My brothers and sisters are peaceful. This is the time before humanity was a spec in the angels eyes, before Lucifer fell."

"You mean Lucifer's in heaven right now?"

Castiel nodded. "The angels didn't bother with the Earth for many millennia."

"Can they...see you here?"

Castiel shook his head. "I've turned off the angel radio and we still have the carvings on our ribs. They won't bother to look outside of Heaven." Sam wondered if it was just his expectations, or if Castiel looked wistful.

"Well maybe you should turn that back on. Ask someone for help?" Sam thought that considering their other options, having a winged angel fly them back to their time would be an optimal solution. The only question was if they could find one who would be willing to help.

"No offense to Cas, but when has getting more angels involved improved the situation?"

Castiel didn't look bothered by Dean's caustic words, but maybe he was just getting used to it by now. "One could make an argument that our situation can hardly get any worse."

"Famous last words," Sam said with a tight little grin that had only a passing relation to a real smile. His head hurt again, a pulsating spike of pain. He probably had a concussion, but they really didn't have time for that. The sprain in his arm was also bothering him distantly, aggravated by all the physical activity of the past hours. He hid his wrist in his jacket's pocket, to keep the swelling out of view. His fingers were freezing, and so were his toes.

It was getting even darker, and the air grew colder. At some point Castiel informed them that night was coming and what Sam had been taking for twilight had actually been the height of the day when sun would have been at its peak. The atmosphere was so polluted it was impossible to tell the time of day without a celestial being at their side supplying it, as certain as though he had a built-in clock.

"We should stop for the night." Castiel said tiredly, seemingly exhausted by their inability to admit that their human bodies were tiring from the relentless pace. "There's some sort of a hole in the face of the rock there." He indicated their right, where Sam could now just barely see a cave's entrance, about the height of an average human and similar in width. "It should provide some cover against precipitation."

Sam, grateful that he didn't have to be the first one to ask to stop, immediately changed his direction to walk towards the cave. Dean didn't argue, which probably meant he was equally exhausted and possibly hiding injuries of his own.

The cave barely earned being called that. It was roughly six feet in length, and even less than that in width. The floor was covered with dirt and some dried out, rotten leaves, probably carried there by the wind that howled loudly outside.

There was no question of them getting any food. Even if they could find an already dead creature to cook on a fire, there was no telling what sixty five million years old meat would do to their human constitution. Besides, they could live without food for several days, especially if Cas could later heal them of any after-effects. What they really needed was water and a way to get home.

Unfortunately, trying to purify rain water for them to drink had made Castiel bleed from his nose again and nearly pass out, so nobody wanted to try that again. Thirsty and starving, Sam and Dean picked their spots to camp out in the cave they had found, as far away from each other as possible to get some modicum of personal space. Prior experience being stuck in confined spaces had prepared them for the inevitable sensation of being stuck in each other's back pockets with no way out. Their flashlight lay turned on between them, pointing inside the cave and shining a pale blue beam that just gave enough light to see each other. They were going to have to turn it off soon, if only to conserve the remaining battery, but nobody wanted to face the total darkness.

To break the silence and fill it with something other than their laboured breathing, Sam asked Cas some questions about the Chicxulub impact that he'd been curious about. He hoped to siphon the knowledge from their friend about an event that had fascinated Sam as a little boy. Castiel spoke at some length about the radiation effects of the asteroid impact, the way the herbivores went extinct first after the plants died out from the lack of the sun. The plants would reseed, but the large animals were gone forever. He spoke of the volcanic activity across the planet that further disordered the already unbalanced food chain. How the way the aerosols and debris stayed in the upper layers of the atmosphere meant that the impact winter would last for many more years. Castiel sounded curiously detached, as though remembering a story someone had told him. But then, perhaps he hadn't been on Earth when these events unfolded, safe up in Heaven. Watching him, Sam felt like he was remembering anew how ancient their friend really was.

Dean sat quietly, without asking a single question. When Castiel stopped talking, that's when he lifted his head, as though he'd just been waiting to say what was gnawing at him.

"I wonder if that wasn't the easiest way for things to turn out," Dean said, not looking at Sam at all. Not looking at Cas either. "Short of passing the Mark to someone else which won't happen."

"What are you talking about?"

"A meteor that made the dinosaurs go extinct could probably take care of me." 

Sam stared at his brother. He tried to contain his expression but it was impossible. Dean glanced at him only once, and had the grace to wince before looking away. Sam glanced at Cas, but the angel was simply watching Dean quietly, no expression on his face.

"Sorry, Sam. It was just a thought that came to mind."

"Yeah, well." Sam looked around for something to hit. He grabbed a rock off the ground and threw it away with more force than necessary, trying to expel his feeling of helplessness that way. "You can forget about it."

"Done and done." Dean said. He sounded tired.

Sam wanted to lay into him, make sure his brother understood that such thinking could get them both killed for real, and not in a fantasy, but Dean started coughing and it was contagious. Soon Sam was hacking up a lung too. He touched his fingers to his lips, surprised not to find blood there. It felt like he'd torn up a lung.

"I could ease your breathing," Castiel suggested.

"Really?" Dean's eyebrows were raised, his voice was like sandpaper. "What, like put a whammy on us? Like hypnosis?"

"That's an adequate analogy," Castiel said. "When we get out of here and I regain my strength, I will heal your bodies wholly, but in the meantime I can trick your minds into believing you are more comfortable breathing."

Sam coughed as he said, "Is it reversible?"

Castiel nodded. 

"The alternative is to keep choking on the aerosols in the air. Your condition will deteriorate more rapidly."

Sam didn't see a downside. He trusted Cas with everything -- almost had to at this point, didn't he? -- and the burning, aching sensation in his chest was impossible to set aside. Sam was no stranger to pain, he knew his own limits and knew that this level of discomfort he could only tolerate for so long. It already felt like this side of eternity. He glanced at Dean, saw the hesitation in his eyes, and volunteered to go first.

"Alright, Cas." He gave their friend an encouraging smile and took a step closer. When Castiel's fingers were an inch away from Sam's forehead he had a flash of suspicious misgiving and glanced at Dean again, but soon controlled the familiar feeling and let the angel's fingers settle gently against his temple. The relief that spread through his body was similar to the coolness of an aloe cream against sun-burnt skin. He grinned towards Dean's doubtful eyes. Took a long overdue deep breath and felt air rush easily through his lungs. "Wow." Even his headache seemed less than before.

Castiel turned his serious face towards Dean, stretching out his arm. Dean's eyes tracked it like it was a snake about to strike and at the very last moment, Dean pulled his face away. "Yeah, no." he only offered for explanation, radiating discomfort.

Castiel's face flashed with sadness that soon turned to understanding. He lowered his hand. Sam wanted to tell his brother that it felt amazing. "Are you sure?" he asked, feeling awkward as the other two observed each other silently. Dean's eyes tracked the path of dried blood on Castiel's face.

"I've been messed with enough already," Dean said. "No offense, Cas."

"None taken," Castiel replied shortly, and Sam could only wonder if that was true. The angel leaned heavily against the nearby mouldy stone, even such a seemingly simple action apparently exhausting to him now. 

"Anyway, I can take it." Dean said, the words as much a macho front as they were the truth. 

"Couldn't you fix my hand too?" Sam asked, rubbing his sore wrist. He'd thought he would be magically better but the headache was still there, and so was the sprain.

"If I trick your pain receptacles into feeling no pain whatsoever that will not end well for you." From where he leaned heavily against the wall, Castiel gave him a look that said he knew about every injury Sam was hiding, and was only keeping quiet as a favour to him.

"Ah." Sam grimaced, but couldn't argue with that. Few things were more dangerous to a human being than having no perception of pain. Besides, if Castiel was too weak to heal them, Sam didn't want to make him pass out. There was a big difference between preventing a few pain receptacles in the brain from processing the information they received and fixing broken tissue and bone.

Sam crouched down at the cave floor, trying to be grateful for the respite he had already received. "I wish we could make a fire and warm up."

"It'll attract the monsters here." 

Unfortunately, Dean was right. They settled in for a silent, cold night.

"I'll take the first watch," Sam volunteered, since he had a pretty good idea that he shouldn't be sleeping with his concussion.

"I do not sleep." Castiel responded, sounded almost offended at the suggestion. "I will keep watch."

Dean, rather than responding, sat down with his legs outstretched in front, and his arms crossed on his chest, the gun lying on his lap and his face angled so he could see the entrance to the cave.

In the end, nobody slept.

 

* * *

 

While trying not to notice the wheezing sounds of their breaths as the night dragged on, that was all Sam could think about. He didn't feel the pain, but the constricted feeling in his chest felt disconcerting. Sam picked up a short stick from the ground and used it to absently scratch patterns in the dirt at his feet. On the other end of the cave Dean was brooding; Sam doubted he was thinking of a way to get back to their own time. Too often lately Dean's thoughts seemed to be occupied more by death and destruction than a way to find a solution. Sam felt like it was all up to him to find a way out. 

He ran through all of their possible allies, trying to think of a way to contact them. If he could think of a spell to summon one of them here, even as a mere image, he could get some information. There were no libraries here with dusty tomes, no Internet, no well of knowledge where Sam felt he could find his answers. Only a burnt, barren land and a bunch of dying monsters. They'd been lucky they hadn't encountered another live one, only the enormous white bones of the dead.

He was so deep in his reflections that he startled when he heard Castiel speak.

"Summoning someone, Sam?" 

Sam looked down at what he was absently charting in the dry dirt and realized that yes, he had been. A summoning circle for an angel. He couldn't think of anything else that would bring them home. Demons had not been created yet, which was just as well. He didn't want to make another deal to save them, he already felt like he was risking far too much trying to decipher the Book with Rowena's help.

"It's nothing," he said and flushed as Castiel's steady blue eyes stayed fixed on him. "Do you think you could find a way to Heaven if you had to?" he asked instead. "I mean, if something happened to Dean and I, and you were alone." What would the other angels think of a wingless angel from the future? Fascination or revulsion was the only thing Sam could imagine.

"I will not let either of you die before me," Castiel said, like this was a given. "There are other beings that exist in this time besides angels that have power."

"Name one," Sam said. Castiel made his way slowly to where Sam's unfinished design was drawn in the dirt and crouched down to examine it. He made a sign with his finger, a squiggle in the middle of the circle that seemed unrecognizable to Sam. There was a flash of lighting outside and Sam turned his head towards the entrance before Castiel could say another word.

Silhouetted against the entrance to their cave stood a tree.

A tree that had not been there before.

"Hey, Cas?" Sam said very calmly, wondering how bad his concussion really was. "What's that?" He pointed.

Cas, however, didn't act as though Sam was hallucinating. The angel perked up and stood from his previously crouching position. He looked curiously at the tree but didn't approach it.

Dean jumped to his feet, turned his flashlight on and shone it at the silhouette. The tree didn't react to the bluish light. It was slightly taller than Sam, with a tightly cropped foliage at the top of the brown trunk, and in the new brightness of the flashlight's beam they could just make out something like a facial structure. 

The tree tilted its head, showing itself to be undoubtedly aware. Dean cleared his throat.

"Hello...Groot?"

What passed for the tree's mouth moved and it said rather snappily: "Clotho." 

The howling wind carried the word like an echo. They seemed to bounce against the walls of their cave. Sam and Dean starred at the tree in silence for a long moment. 

Sam squeezed his eyes shut, then re-opened them. The talking tree was still there. It had sounded like a matronly female, if such a thing was possible. It stared silently at them now, seemingly observing. "Dean?"

"Yeah?" Dean wasn't taking it's eyes off it.

"Remember that Lord of the Rings marathon we had with Charlie? Do you think I fell asleep during that and this is all an elaborate nightmare?"

Now that he was looking more closely, he could identify the limbs that passed for hands sprouting from the creature's torso, the rough brown bark looking dry and cracked. In one arm-branch, the tree held some kind of a wooden instrument, a stick with something shiny and bright wrapped tightly around it.

Castiel stepped forward and nodded a deferential greeting. "I am Castiel."

The tree observed the angel with a singular focus now. It's hollow eye-slits didn't hold an expression but gave the appearance of constantly tracking your every move all the same.

"Clotho is one of the three Fates," Castiel gave an explanation in a quiet voice meant only for the two of them. "We've met her older sister. Atropos."

"She didn't look like a tree," Dean put in. Sam had wondered about that himself, but humans hadn't been born yet. If the alternative was the goddess looking like one of the other creatures that inhabited this millennium, he could deal with a little foliage. 

Castiel shot his brother a warning look, but then acceded and explained. "Atropos is the smallest of the Fates, but also the most connected with humanity since she determines when the thread of life is cut." He glanced at Clotho, but the goddess was still as a sphinx (or an actual tree) while she observed them, "Clotho is the one who spins the thread." He nodded towards the instrument in the tree's arm, which Sam now recognized as a simple wooden spindle.

"And my threads have become tangled up," she said. Her voice made their little cave feel like a deep canyon, carrying and echoing off of every surface, reverberating as though the dead forest itself was repeating her words back to them. It sounded like a warning.

Sam glanced around them, feeling unease. Their cave only had a single entrance. The last twelve hours hadn't been a picnic and he had thought he was too worn out to feel dread anymore. Still, an unnamed foreboding crawled up his spine as Clotho's dark eyes watched their faces. If they had to make it past her, if they had to run, Sam wasn't sure he could do it. His head was splitting. He took a deep breath, packing up the pain into a tiny corner of his perception.

"We didn't mean to interfere with your work," he tried.

"We never do," Dean quipped, in what only he thought was a helpful manner.

Sam took a step forward, to get Clotho's attention on him in case Dean managed to offend her somehow and made her kill them, or worse, leave them here.

"You've come here...or you've been summoned...but I know that someone as powerful as you must know how we can set this right. How do we get back?"

If trees could shrug, the sound of it was in her voice. "There are ways."

Sam clamped down on his instinctive irritation. Softened his voice even more. "Can you help us?"

Clotho ignored Sam and looked right at Dean. "You can stay in the darkness with me."

Sam could sense his brother's discomfort without looking. "My brother and I can't live here. We have to get back. We can't stay."

Dean backed him up. "We're leaving. And the angel is coming with." He came to stand next to Sam, tilting his head in a challenging fashion. "Do you even have the power to bring us back?"

Clotho's laugh was like a roiling tornado.

"Easy...like untangling a thread." She made a motion with the arm-branch and they vanished.

 

* * *

 

They reappeared in the same warehouse as before, where Magnus' workshop still stood untouched. Disoriented by the change of scenery, Dean almost reached for the shelf next to him but flinched and withdrew his hand. 

"Don't touch anything!" he told the others, looking around and seeing both Cas and Sam safely on their feet. Sam glared his feelings about that order, but the statuette was no longer in the box on the shelf. Perhaps Clotho had made it go away so that no more of her threads would become tangled up. Perhaps it was a one-time-use artifact that had vanished after it had used up its magic. Sam was glad they wouldn't have to dispose of it in any case, because he wasn't sure how to do that. The air in the room smelled like the library, familiar and sweet compared to what he'd been breathing for the past ten hours.

Looking down at his dirty hands and dirty clothes, Sam was just as happy his only concern for the next couple of hours was getting horizontal. No more talking tress, or goddesses or fate. No more primordial monsters for at least four hours.

And speaking of Clotho....

"She told me to stay," Dean said. "That was something you guys caught, right?"

Sam nodded. "No idea what that was about." They both glanced at Cas.

"Me neither." Castiel replied. "I do not know how she thinks. I have not personally encountered her before."

Sam was still curious, despite how badly his head hurt. "What do you know about her?"

"Clotho and the other Fates were born out of union of Erebus and Nyx. Those were the personifications of Darkness and of the Night, both born of primordial Chaos..." Cas seemed to think for a moment, but eventually shook his head. "I cannot interpret her meaning."

"Well, she is much older than you, Cas." Dean said glibly, giving him an out.

Castiel nodded.

"She and her sisters are powerful. It was risky to summon her. It would be best if our paths did not cross theirs again."

"I'll drink to that."

Sam nodded, then clutched his head. It hurt even more than before. 

"You know what guys?"

"Yeah?"

"I think I'm gonna pass out." He did.

When he woke up in his bed much later, healed and well-rested, covered with a soft cotton comforter, Sam had a curious thought. His life might be fantastical and weird, but a constant ran through it like a current.

They always found a way through.

 

* * *

 

**Fin.**

**Author's Note:**

> While doing research for this fic I ended up reading numerous academic papers about the Chicxulub impact. The only thing recent research seems to agree on is that the asteroid impact and the impact winter by itself should not have been entirely responsible for the extinction, although it was almost definitely a major contributing factor. Deccan volcanism is proposed as one of the other possible events leading to the extinction of dinosaurs. I enjoyed reading the research papers on the simulations of the event, such as acidity of the oceans over the years, the concentrations of aerosols in the atmosphere, the likely global firestorms that resulted and so forth. In the spirit of learning more about this event, if you think I got things wrong in the story, feel free to leave a comment to that effect.
> 
> And of course, please leave your comments or kudos to let me know if you've enjoyed this story!


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